'I'm a dietitian – here's why these common diet myths don't hold up'
From detoxing to cutting carbs, here are some of the most common dieting myths out there and why you shouldn't fall for them.
By Tai Ibitoye
As a registered dietitian and a university lecturer in nutrition and dietetics, I speak, think and hear about food and nutrition all day, every day. I have heard so many myths and misconceptions about food over the years – not only in consultations but also at wellness events, among family and friends, and even when eavesdropping on conversations during my morning commute.
There’s so much misinformation in the nutrition space right now – especially since the rise of health influencers on social media. Every day I receive at least one direct message asking me to confirm whether a particular diet-related post is true or false.
Here are six of the most common diet myths I’m constantly faced with, and why you shouldn’t believe them.
‘Stay away from carbs – they’re fattening’
This myth couldn’t be further from the truth. Gram for gram, carbs (carbohydrates provide 4 kcals per gram and fat provides 9 kcals).
Even though excluding carbohydrates from a person’s diet can lead to weight loss – like any other dietary restriction – the weight loss could be, in part, due to rather than losing fat. Also, remember that rapid weight loss is not necessarily healthy and diets which cut out major food groups usually prove not to be sustainable, with people .
Carbohydrates are essential macronutrients and a primary source of energy for the body. Foods containing carbohydrates provide us with a range of vitamins, minerals and fibre which are important for our general health and wellbeing. The Science Advisory Committee on Nutrition (SACN) recommends that carbohydrates should form for the general population.
Instead of cutting carbs from your diet, opt for wholegrain varieties, like those you’ll find in wholemeal bread, wholewheat pasta, brown rice, fruit, vegetables and potatoes with their skin on. By doing this, in addition to improving your satiety levels – which is helpful for weight management – you’ll be increasing your intake of fibre, something 90% of us aren’t getting enough of.
‘Sugar in fruit is bad for you’
In recent years, fruit has become unnecessarily villainised because of the type of sugar it contains. Fructose is a naturally occurring sugar found in all fruits, and while research has suggested that a high intake of fructose is linked with an imbalance of , it’s important to take a closer look before you consider any changes to your diet.
There are two important points to explore here. Firstly, most of these studies have been observational so we can’t yet be sure that fructose alone causes these effects. Secondly – and perhaps more importantly – these studies mainly investigated the effects of high-fructose corn syrup (HCFS) which is completely different from the fructose found in fruit.
The sugar in whole fruit is contained within its cell structure so is not classed as , which is the type that many of us need to be mindful of. Free sugars are the kinds that are added to food or drink to sweeten it, and the type you find in juice, syrup and honey.
In fact, consuming fruit alongside vegetables has been associated with having a of developing conditions such as high blood pressure, heart disease and some cancers.
Plus, fruits are a great source of vitamins, minerals, phytochemicals and fibre – all of which are important for good health.
We should aim for at least a day. Fruit juice does contribute towards our five-a-day, although only ever as one portion – no matter how much you drink. It’s important to remember that the fibre is mostly removed in these drinks and the natural sugars count as ‘free sugars’ (because of the juicing process – the same goes for fruit smoothies). So, we should have no more than one small glass (150ml) a day.
‘Detox diets rid the body of toxins’
We’re frequently confronted by detox diets online, making big claims about how they will cleanse you of toxins. As such, they are especially popular after a period of over-indulging, like Christmas or when people are trying to ‘reset’ their body, for example, before going on a summer holiday.
Many detox diets are potentially dangerous and restrictive, and are not based on robust scientific evidence. Claims made are often exaggerated too, with any benefits .
Your body is well-designed to remove waste products and toxins itself. Unless you have a serious medical condition, your gut, liver and kidneys will detox the body by responding to physiological signals – no specific food, drink or supplement is required.
While some detox diets encourage increasing fruit and vegetable intake and reducing your intake of foods high in saturated fat, salt and sugar (which is no bad thing), they also regularly encourage excluding entire food groups. This is unnecessary in most cases and could actually result in .
It is best to enjoy a healthy and varied diet, get enough sleep, be mindful of alcohol intake, don’t smoke, get fresh air and be active rather than following a detox diet. If you think you might have a food allergy or intolerance, then speak to a doctor for proper diagnosis and a registered dietitian for tailored dietary advice: don’t be tempted to try a detox diet to rid yourself of symptoms.
‘Vegan and vegetarian products are healthier’
A well-planned vegetarian or vegan diet can be nutritious and support healthy living. However, just because a food is vegetarian- or vegan-friendly, it certainly doesn’t mean it is the best or healthiest option.
Some vegetarian and vegan food products are ultra-processed and can be very high in saturated fat, salt and sugar. For example, a vegan ice cream may contain similar amounts of sugar to dairy ice cream, and some meat substitutes like soya burgers and soya sausages (although a good source of protein) can often be high in salt and fat, so should be consumed in moderation.
It is important to read nutrition information labels to help you choose between products. In addition to this, be mindful of how vegan and vegetarian meals are prepared, such as frying instead of baking and adding extra ingredients that could contribute towards your saturated fat, salt and sugar intake.
‘Avoid dairy – it’s not needed in your diet’
Dairy products can form part of a healthy, balanced diet. They are highly nutritious as they are excellent sources of protein, calcium, iodine, phosphorus, potassium and B vitamins. Also, some types of fermented dairy foods like bio-live yoghurt and kefir contain probiotics which can support gut health. Dairy contains a natural type of sugar called lactose, but this does not count as those ‘free sugars’ that we need to limit, because it is combined with important nutrients.
Unless you have a dairy allergy or intolerance diagnosed by a qualified medical professional, then you do not need to cut dairy foods from your diet. And if you choose to avoid dairy for other reasons – for example to follow a vegan diet – you need to ensure your diet contains non-dairy products that are fortified with the likes of iodine, calcium and B vitamins.
‘Individual ingredients and supplements can boost your immune system’
There are many essential nutrients that keep our immune systems working well – but they all work together. So, it’s important we don’t become fixated on a single nutrient like zinc or vitamin C when there are other nutrients (including copper, folate, iron, selenium, vitamin A, B vitamins and vitamin D) that have important roles to play in immunity. Eating a healthy and varied diet which includes fruits and vegetables, wholegrains, dairy products (or fortified alternatives), nuts and seeds, meat, fish or plant proteins like beans and pulses is enough to support our immune systems in most cases.
There are some people who might need to take certain dietary supplements, such as those who are planning to become (or are) pregnant, individuals at risk of vitamin D deficiency and some people on a vegan diet.
It is also important to keep in mind that adequate sleep, regular exercise and keeping stress at bay can also help maintain good immune function.
So, next time you see a health ‘fact’ on social media, take a look to see who’s behind it and double check whether the science really does stand up.
Please note: Information is not intended as a substitute for proper medical diagnosis or dietary advice provided by your dietitian. Please always seek advice from a dietitian for tailored dietary advice and support.
Originally published April 2023
